i40e: fix up VXLAN messages

When the VXLAN ports are added and removed, the messaging was giving some
bogus index info, the port was always '0' for the delete, and the message
text style didn't match other messages in the driver.  Also, there was an
over-use of the tertiary statement which made reading a little harder
than necessary.

Change-ID: Ie805182a697b8b4c12024403ada87fd4e4fa2358
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>